This invention relates to a reproduction method of a filter demineralizer of a condensate cleanup system in a nuclear reactor power plant, particularly to a method of reproducing the filter demineralizer by reproduction of powdered ion-exchange resin precoated and reusing it.
A boiling water reactor (BWR) uses water condensed in a turbine as coolant thereof. The condensed water or condensate is contaminated with corrosion and erosion products (crud), impurities in incoming water, etc. For the purpose of maintaining clean condensate quality, there is a condensate cleanup system which comprises a filter demineralizer and a condensate demineralizer. The filter demineralizer has a plurality of cylindrical filter mediums arranged in a cylindrical container to filter the condensate therethrough. The filter mediums each comprise a nylon net or the like wound on the outer face of a cylindrical holder with a plurality of throughholes, and a powdered ion-exchange resin layer.
The condensate flowing into the filter demineralizer contains about 60.about.80 ppb of iron components of a time of a transitional operation after starting of the reactor operation, and several hundred ppb.about.several ppm of iron components at a time of the usual operation. The iron components include iron crud and iron ions. These iron components are caught by the nylon element and the powdered ion-exchange resin layer. When the iron components are accumulated on the filter mediums by some extent (or after running for a certain time), a pressure drop experienced or evential breakthrough of the iron components from the filter mediums occurs. Therefore, the powdered ion-exchange resin precoated is replaced by new ion-exchange resin, whereby reproduction of the filter demineralizer is carried out. The contaminated ion-exchange resin is discharged out of the condensate cleanup system as waste together with other waste. The waste, which is contaminated with radioactivity, is transferred to a radioactive-waste disposal equipment, reserved there to go into decay, and finally hardened filled in drums.
The number of the drums filled with the used ion-exchange resin is large and reaches to about 60% (percent) in its ratio to that of all the drums filled with the waste generated in the nuclear reactor power station (it is deduced to become 2,000 drums every year in a power plant of the scale in which 1,100 MWe is generated). Such a large number of the drums present large problems, one of which is great expenditure for disposing of the waste, and another is large storage place for the drums difficult to obtain. Therefore, it is desired to minimize the waste discharged out of the system or plant.
As a prior art, there is a U.S. Pat. No. 3,849,196 filed on Nov. 19, 1974. This is concerned with "Ultrasonic Cleaning of Resin" in which contaminated ion exchange-resin is cleaned up by using ultrasonic energy. A similarity between the invention and the U.S. patent is to clean up the ion exchange resin contaminated with crud.